NCPAP FOR THE TREATMENT OF OBSTRUCTIVE SLEEP APNEA
ADEMIR BAPTISTA SILVA * — HÉLIO LEMMI **
SUMMARY — Nasal continuous positive airway pressure (NCPAP) represents a real advance in the management of obstructive sleep apnea (OSA). Our data show that except for awakenings, all sleep and respiratory parameters were significantly improved (p<0.05) in favor of the group treated with NCPAP. A main problem with NCPAP is the acceptance by the patient; it also may disturb the sleep, at least, on short term basis and, in a small number of patients, it does not correct the apneas. In our patients series, males responded better to NCPAP than females.
Tratamento da apnéia obstrutiva do sono pelo N C P A P
RESUMO — O tratamento da apnéia obstrutiva do sono pelo NCPAP (pressão positiva contínua nasal) vem se tornando rotina, pois este tratamento substitui a traqueostomia em muitos casos. O NCPAP, às vezes, não é tolerado pelo paciente, constituindo este fato um óbice ao seu uso mais abrangente. De maneira geral, todos os índices da polissonografia mostraram modificações estatisticamente significantes, exceto para o número de despertares completos. Este fato indica que os parâmetros que avaliam a qualidade do sono não seguem aqueles que avaliam a função respiratória em alguns pacientes. Em pequeno número de pacientes, esta modalidade de tratamento não funciona. Por outro lado, nossos dados reve-laram que os pacientes do sexo masculino respondem melhor ao NCPAP que os do sexo feminino e que o quadro da apnéia é mais grave no grupo feminino, aparecendo mais precocemente. Estes dados são preliminares e foram obtidos para uma amostra pequena, necessitando de confirmação em uma série maior de pacientes.
Three new treatments for O S A S have appeared lately in the medical litera-ture 2,11,13, Uvulopalatopharingoplasty ( U P P P ) , gastroplasty and N C P A P were intro-duced to substitute tracheostomy, previously, the only effective treatment available 1.3,5,6.
Gastroplasty and U P P P have specific indications respectively morbid obesity and redundant oropharingeal tissue. Because N C P A P has a more wide range of indications, in our Center, patients with OSA are routinely tried on this form of treatment. Some patients are treated with N C P A P on a temporary basis, until a more definitive treatment such as U P P P or weight reduction is accomplished. Long term follow up of patients responsive to N C P A P have been reported 8-10,12. Our analysis in this study is in reference to the effectiveness of N C P A P on a short term basis.
METHODS
We studied 22 patients, evaluated at Baptist Memorial Hospital Sleep Disorders Center in Memphis, who were tested with NCPAP the night following the diagnostic polysomno-graphy (PSG) documenting OSA. The PSG consisted 01 the electroencephalogram (EEG) recorded from C3-A2 and C4-A1, chin-electromyogram (EMG), leg-EMG, nasal and buccal
From Baptist Memorial Hospital Sleep Disorders Center (Memphis): * Fellow from Escola Paulista de Medicina (São Paulo) with grant from CNPq; ** Director of Sleep Disorders Center.
NCPAP for obstructive sleep apnea 151
thermocouples, thoraxic and abdominal strain-pauses and blood 02 saturation monitoring. The PSG were recorded in noise attenuated room with constant temperature around 23°C. The patients were monitorized by low light video-camera with infra-red illumination as well microphones. The analysis of the recordings were done according to Rechtschaffen and Kales criteria (7). The data were submitted to statistical analysis by Wilcoxon rank test, comparing before and after treatment indexes. For the purpose of this research, we
considered the apnea index ( A l ) , the number of apneas per hour of sleep, less than 5 for males and up to 1 for females as being normal. The target point of maximum improvement for normal sleep were the parameters set forth by Williams et al. Vr
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RESULTS
The clinical and Polysomnographie characteristics of our sample are presented in tables
1 to 4.
Sex n Age (yrs) range W T (lbs) range HT (ft) range
Male 16 49.2 (28-75) 243.7 (180-345) 6'10" (5'7"-6*4")
Female 6 37.0 (31-61) 267.8 (179-338) 5'4" (5'l"-5'6")
Table 1 — Clinical characteristics of the patients with OS A. WT, weight; HT, height; n, number of patients.
Parameter Before sd After sd P ^ 0 . 0 5
Apnea Index 45.0 28.0 8.0 10.0 s
02 saturation % 64.6 12.9 84.9 8.5 s
* of arousals 287.6 186.4 56.9 44.0 s
* of await en ings 4.2 2.6 5.0 5.0 ns
Slow wave sleep % 6.7 2.6 21.7 5.0 s
Table 2 — Sleep parameters before and after NCPAP. sd, standard deviation; s, significant; ns, non significant.
Sex Effective Partial Ineffective Not tolerated
Male 12 2 1 1
Female 1 3 2 0
Tabic 3 — NCPAP effectiveness according to sex.
Parameter Improved Worsened Not changed
Arousals 21 1 0
Awakenings 7 10 3
Slow wave sleep 19 3 0
COMMENTS
N C P A P worked very well for all sleep parameters, except for the number of awakenings. It is interesting to note that males with apneas predominate over females, but apnea indexes were higher in females. The mean age w a s lower for females than for males. Females were heavier than males, even without weight correction for sex. N C P A P w a s more effective for males than for females, when measured by apnea indexes after treatment. While not all patients improve on N C P A P 14, it has become the most important short term treatment for obstructive apneas in addition to being effective a s long term therapy for some patients 4.9.10. In this present series, 3 patients didn't improve on N C P A P and 1 did not tolerate it. Partial improvements were observed in 5 cases. The patients who did not respond to N C P A P as measured by apnea index had continued to have abnormal sleep parameters. On the other hand, patients who improved their apnea indexes on N C P A P either did not improved the sleep parameters or in some cases even became worse ( T a b l e 4 ) , a fact that is of some concern in long term N C P A P therapy. T h i s problem may impact long term compliance rate.
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